Project Summary Despite previous success in reducing alcohol impaired driving (AID), rates of alcohol-related motor vehicle crashes have not decreased significantly since the 1990s. Developing novel approaches to prevention/intervention is likely required to produce further progress. Building on laboratory findings from the original project (Acute Alcohol Effects on Impulsivity and Risk for Drinking and Driving), the proposed project is designed to bring this work out of the lab and into the natural drinking environment in which AID decisions are made. Participants will complete a laboratory alcohol administration session followed by six weeks of multi-method ambulatory assessment. The ambulatory assessment component will include participant report via smartphone, transdermal alcohol concentration (TAC) using the BACtrack biosensor, and location and movement data passively collected by the smartphone GPS/accelerometer. The combination of these methods will allow for the integration of subjective (e.g., perceived intoxication) and objective (e.g., TAC, calculated drinking location) data for each drinking episode. Aim 1 of the project is to test laboratory measures as prospective predictors of AID and examine the role of event-level influences on specific AID decisions. Aim 2 of the proposed project is to test the potential for a novel intervention to reduce AID using mobile technology. Participants will be randomly assigned to either a full ambulatory assessment or a minimal assessment control condition. The timing of the introduction of AA will also be manipulated within the full ambulatory assessment condition. This design will allow us to test whether the introduction of ambulatory assessment produces changes in AID behavior, as well as whether such changes persist once ambulatory assessment is discontinued. Changes made to the revised application are aimed at ensuring the achievement of both study aims. If Aim 2 is achieved and ambulatory assessment alters AID behavior, the combination of the minimal assessment control condition and the full assessment condition prior to the introduction of ambulatory assessment has sufficient sample size and power to test Aim 1 hypotheses.